"Frack" is a minced oath for "fuck", as Fraser says, but "snap" does not mean shit. "Snap" is an interjection conveying surprise and admiration, something like "wow".
– MalvolioJul 26 '11 at 22:50

If everyone knows what you mean when you substitute terms (nudge, nudge; wink,wink), then the offensiveness of the remark might actually be improved because of the cleverness by which you pretend to conceal the true meaning.
– Sonic-Q-TipAug 11 '11 at 11:10

Why the downvote? The substituted words are euphemisms for the word being substituted.
– GnawmeNov 15 '11 at 18:24

1

@Gnawme: I'm guessing because someone thinks the only correct answer is "minced oath". So far as I'm concerned euphemism is equally correct, so it's a shame they're two separate answers. Luckily I can spare the upvotes for both!
– FumbleFingersNov 15 '11 at 19:28

@FumbleFingers: More to the point: "Minced oaths are a sub-group of euphemisms used to avoid swearing when expressing surprise or annoyance." Phrase Finder
– GnawmeNov 15 '11 at 19:34

This word proposal seems like the only word which would actually be used in conversation. No one is going to say "What a unique minced oath/bowdlerisation!" whereas someone may actually say "What a unique euphemism!"
– ChrisMNov 16 '11 at 17:59

Q: At what point do the made up words turn into recognized/official words? For example I'm pretty sure I can use most of the above replacements and people will know what I mean, fricking and fracking being most used.

English has no official arbiter of words, so it depends what you mean by recognised and official. It just depends on usage. Once a word is used widely enough then almost by definition, most people will understand it.

Q: Even if a replacement becomes commonly used, at what point would it end up in say the OED?

It doesn't really matter if the words are slang or offensive, it again depends on usage. The OED has a FAQ on how a word qualifies for inclusion. Briefly, if a word has been used by enough people, and/or for long enough, then it's in.

Of your examples, fricking, fracking and freaking are already in Oxford Dictionaries Online as vulgar slang used as euphemisms for fucking. Smurfing and frelling aren't there, but these are less well known.

Another common term is "minced oath". This term literally refers to a substitute for the profane rather than the obscene or vulgar, however, I think it is sometimes used as a more general term for any such substitution.

So "gosh darn it", a minced oath for "God damn it" would be literally a minced oath. But "shut the front door", a substitute for "shut the f*** up" would not be an oath, and so not literally a minced oath. But I think the term is applied to both.

If the swearing is an interjection/exclamation, or has no real meaning in the sentence, it falls in the category of expletives

expletive

1 a: a syllable, word, or phrase inserted to
fill a vacancy (as in a sentence or a metrical line) without adding to
the sense; especially a word (as it in “make it clear which you
prefer”) that occupies the position of the subject or object of a verb
in normal English word order and anticipates a subsequent word or
phrase that supplies the needed meaningful content

b : an exclamatory word or phrase; especially one that is obscene or profane

"Polite ones", as the one you mentioned, are known in most literature as moderated expletives or euphemistic taboo expletives. You can see both uses and read more about here in this book

Maybe the term you are looking for is called "Bleep". It is used in TV where a person says a word that might be not appropriate for viewers. However since that is a matter of opinion, I guess you can use it like it is "a key to every lock" type of thing.

"Bleep" is an interesting example. Originally, they would just cut the audio, but people would think that it was a technical flaw, so they would replace it with a sound. That sound was onomonopiacally named "bleep", and the act called "bleeping". Now the word "bleep" has itself become a minced oath and people literally say, "What the bleep is going on?"
– MalvolioJul 20 '12 at 18:10

@Malvolio The bleep used to cover words also has explicit rules, such as the frequency and how much of the word must be covered. Interesting, but not related to what you are saying.
– fredsbendFeb 5 '14 at 23:55

@fredsbend -- "Unnecessary censorship" (actually, censorship that is not only unnecessary but so excessive as to create a humorously false impression of obscenity) is now a popular thing. See here for a hilarious example (although, if my ears do not deceive me, they are subtly cheating by adding not only a bleep but a subtly "f" sound).
– MalvolioFeb 6 '14 at 1:21

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